U.S. Pat. No. 5,291,271 discloses an apparatus and method for electro-optically measuring the thickness of a container wall. A light source directs a light beam onto the outer surface of a container at an angle such that a portion of the light beam is reflected from the outer surface, and a portion is refracted into the container wall, reflected from the inner wall surface and then re-emerges from the outer wall surface. A lens system is disposed between a light sensor and the container wall for focusing light energy reflected from the outer and inner wall surfaces onto the sensor. The container is rotated around an axis, and information processing electronics are responsive to the light energy incident on the sensor for scanning the sensor at increments of container rotation and determining wall thickness of the container between the inner and outer wall surfaces as a function of the separation between the points of incidence of the reflected light energy on the sensor. Light energy reflected from the outer surface of the container wall also provides information concerning wall contour around the container as a function of container rotation at the location at which the light energy is incident on and reflected from the wall surface.
The present disclosure embodies a number of aspects that can be implemented separately from or in combination with each other.
Apparatus for inspecting contour of a container sidewall, in accordance with one aspect of the present disclosure, includes at least one light source for directing light energy onto the container sidewall and at least one light sensor disposed to receive light energy from the light source reflected from the container sidewall. The light sensor is responsive to such reflected light energy to provide signals indicative of position of the container sidewall relative to the sensor at at least two locations on the container sidewall spaced from each other in the direction of the container axis. An information processor is responsive to such signals to determine contour of the container sidewall in the direction of the container axis as a function of sidewall positions at such locations. The at least two locations on the container sidewall preferably are nominally aligned with each other in a direction parallel to the container axis. One of the locations on the container sidewall preferably is adjacent to the container shoulder or the container heel, and another of the locations is on the container sidewall between the container shoulder and the container heel.
In the preferred embodiments of the disclosure, the at least one light sensor provides signals indicative of position of the container sidewall relative to the sensor at at least three locations on the container sidewall spaced from each other in the direction of the axis of the container. The information processor preferably detects variations in contour at the container sidewall as a function of the departure of the sidewall position at one of the three locations from a line between the sidewall positions at the other two of the three locations. Such other two of the three locations preferably are respectively adjacent to a heel and a shoulder of the container, while the one location preferably is between the container heel and shoulder. The container preferably is rotated around an axis, and the first, second and third locations preferably are nominally aligned with each other in a direction parallel to such axis. The sensors may comprise individual sensors disposed to receive light energy reflected from the container sidewall at the three sidewall locations, or an area array sensor disposed to receive light energy reflected from all three of the sidewall locations.